1. Field of the Invention
This invention relates to a process for producing a magnetic recording material, more specifically, to a process for producing a magnetic recording layer of a magnetic recording material having a magnetic recording layer formed by coating.
2. Description of the Prior Art
According to conventional techniques, magnetic recording materials of the type in which the magnetic recording layer is formed by using a coating liquid are produced by kneading a ferromagnetic powder, a binder resin, additives and an organic solvent, mixing and dispersing them thoroughly using a dispersing machine, coating the resulting solution on a support, such as a plastic sheet, metal foil or paper, and drying the coating.
Use of organic solvents has recently led to various problems such as increased product cost due to increased organic solvent cost and the necessity for taking measures to protect against fire, pollution and toxicity to working personnel.
In an attempt to solve these problems, a method was suggested in which the magnetic coating composition is prepared in the form of an aqueous emulsion, for example, as disclosed in Japanese Patent Publication No. 46922/74. According to this method, an aqueous emulsion of a synthetic resin and a water-soluble adhesive is used. However, these materials can be applied only to a non-magnetic paper support because the former component has insufficient adhesiveness and strength, and the latter component does not have sufficient water resistance and strength. This method, therefore, is not applicable to non-magnetic supports such as plastics, metals or ceramics.